An OVPN is a new service application that emerges while the optical network transforms to an Automatically Switched Optical Network (ASON). It is a dynamically creatable network that operates across multiple managerial wavelengths, and provides the user with Virtual Private Network (VPN) services on the transport layer. Generally, such an OVPN is called a VPN (L1 VPN).
The OVPN enables the operator to divide an optical network into multiple sections available to multiple terminal users, and provide the comprehensive and secure capabilities of viewing and managing the user's own OVPN as if each user owns his own optical network. Therefore, users can build their own network topology in the public network flexibly at lower communication costs. With an OVPN, the operator can optimize the bandwidth utilization ratio, and provide more flexible and versatile wavelength services different from the usual monotone bandwidth service. The OVPN posses the merits of cost-efficiency, flexibility, reliability, security, and expansibility. Therefore, the OVPN services become the most promising value-added services (VASs) in an intelligent optical network, and provide new profit growth points on the existing networks for the operators.
FIG. 1 shows the structure of an OVPN. As shown in FIG. 1, an OVPN contains a Provider Edge (PE) equipment connected with the Customer Edge (CE) equipment. In the L1VPN, the PE is generally an optical network equipment, such as Optical Cross-Connect (OXC) equipment, and the CE is generally a client-side equipment, such as a router or a switch. Multiple PEs communicate with each other through an optical network to implement interworking between CEs.
In the example shown in FIG. 1, CE1 and CE2 are connected to PE1, CE3 and CE4 are connected to PE2, and PE1 is connected to PE2. Communication is required between CE1 and CE3 in the working time segment of 4:00˜24:00 (T1); communication is required between CE2 and CE4 in the time segment of 00:00˜4:00 (T2) at dawn. T2 is generally used for backing up data, and the bandwidth occupied by T1 is the same as that occupied by T2. In this way, PE1 must provide two ports connected with CE1 and CE2, respectively; PE2 must also provide two ports connected with CE3 and CE4, respectively. The bandwidth is multiplexed with respect to time in an OVPN. In order to implement service handover, the operator releases the bandwidth by releasing the path between CE2 and CE4 in the time segment T1, and uses the released bandwidth to create a path between CE1 and CE3. Likewise, in the time segment T2, the operator releases the bandwidth by releasing the path between CE1 and CE3, and creates a path between CE2 and CE4.
In the previous OVPN system, the port connected with the CE on the PE may be an optical interface of the Wavelength Division Multiplexing (WDM) equipment or an optical interface of the data board of the Synchronous Digital Hierarchy (SDH) equipment, and is costly. Since each PE occupies many ports, the networking costs of the OVPN are high. Moreover, for optical network equipment, if the services of different CEs do not change in the network of the operator in the working time segment after handover compared with those in the working time segment before handover, the operator must adjust the network route due to service handover although the communication bandwidth and path do not change within the time segments T1 and T2. In the process of adjusting the route, the reconfiguration of cross-connections leads to intermittency of services, thus affecting the Quality of Service (QoS) of the network.